#include<unistd.h>
#include<stdio.h>
#include<string.h>
#include<stdlib.h>

#define MAXL 1024

int main(void)
{
	int n, int1, int2;
	char line[MAXL];

	while((n = read(STDIN_FILENO, line, MAXL)) > 0) {
		line[n] = 0;
		if(sscanf(line, "%d%d", &int1, &int2) == 2) {
			sprintf(line, "%d\n", int1+int2);
			n = strlen(line);
			if(write(STDOUT_FILENO, line, n) != n)
				err_sys("write error");
		} else {
			if(write(STDOUT_FILENO, "invalid args\n", 13) != 13)
				err_sys("write error");
		}
	}
	exit(0);
}
